Heirs of the composer for Marvin Gaye’s Let’s Get It On sued British musician Ed Sheeran, claiming his hit song Thinking Out Loud copies core elements of the late soul singer’s 1973 track.

The copyright infringement lawsuit was filed by the heirs of Ed Townsend, who co-wrote the lyrics to Let’s Get It On in 1973 and created its musical composition, according to the complaint filedin federal court in the Southern District of New York.

Representatives for defendants Sheeran, Sony/ATV Music Publishing and Atlantic Records did not immediately respond to requests for comment.

The lawsuit, which asks for damages to be assessed at a jury trial, argues that the harmonic progressions, melodic and rhythmic elements central to Let’s Get It On formed the structure of Sheeran’s Thinking Out Loud.

“The defendants copied the ‘heart’ of Let’s and repeated it continuously throughout Thinking,” the lawsuit said. “The melodic, harmonic, and rhythmic compositions of ‘Thinking’ are substantially and/or strikingly similar to the drum composition of Let’s.”

Grammy Award-winning Sheeran has become one of Britain’s top-selling artists in the past two years, and has written and co-written tracks for artists such as One Direction, Taylor Swift and Justin Bieber.

The lawsuit came two months after California-based musicians sued Sheeran for $20 million over his hit song Photograph in an unrelated case. Gaye’s family last year successfully sued R&B recording artists Robin Thicke and Pharrell Williams for copyright infringement in another unrelated case over their hit single Blurred Lines, winning a $7.4 million judgment.